Mowing devices having a rotatable cutting reel for mowing grass or other vegetation are well known. The cutting reel usually comprises a plurality of curved cutting blades rigidly secured together for rotation as a unit. An elongated bedknife extends along the length of the cutting reel and cooperates with the cutting blades as the blades pass over the bedknife to sever the vegetation. In effect, the vegetation is sheared off as the cutting blades press the vegetation up against the fixed bedknife and then sever the vegetation.
The bedknife and cutting reel must be properly positioned relative to one another for this type of mowing apparatus to function properly. Many of those skilled in this art believe that there should be some contact between the bedknife and the cutting blade. However, such contact should be kept within a precise range. Too much contact results in undue wear on the bedknife and cutting blades and also decreases the quality of cut. Too little contact results in a poor quality of cut.
Many of the prior art reel type mowers have utilized some type of means for adjusting the position of the bedknife relative to the cutting reel or vise versa. The great majority of these adjustment systems comprise threaded screws or the like for physically moving the bedknife towards or away from the cutting reel. Such systems must be manually adjusted before a mowing operation begins. Usually, the operator of the mowing apparatus has to disengage the cutting reel from its drive and then rotate the cutting reel by hand so that the blades of the reel pass over the bedknife. Then, using experience and listening to the sound of the blades as they pass over the bedknife, the operator then rotates the adjustment screw until he feels that the bedknife is properly positioned. Sometimes, a piece of paper inserted between the bedknife and the cutting reel is used to determine when the bedknife is properly positioned by looking at how the cutting blade severs such a piece of paper.
This method of adjusting the cutting reel relative to a bedknife has numerous flaws. Since the determination of when the bedknife is properly positioned is totally subjective, an experienced operator must usually make the adjustment for it to be correct. Inexperienced operators cannot usually properly adjust a edknife with any degree of reliability. Insofar as such an inexperienced operator does not correctly adjust the cutting reel, undue wear or poor quality of cut will result.
Moreover, even for an exxperienced operator, this adjustment procedure is relatively time consuming. It requires a careful manual adjustment of each cutting reel by turning the cutting reel by hand and listening to the sound of the cutting blades and then adjusting, as many times as may be necessary, the position of the bedknife to achieve the right sound. This can take a few minutes for an experienced operator and much longer for an inexperienced one. The labor spent in such an adjustment operation is significant especially when one considers that many devices have a plurality of these types of cutting units. For example, The Toro Company, which is the assignee of the present invention, manufactures some products which carry up to seven cutting reels. Considerable man hours can thus be spent in adjusting such cutting reels. This is disadvantageous.
Another disadvantage of the manual method of adjusting a bedknife to a cutting reel is that this adjustment must be done while the machine is shut down. It is usually done before the mowing operation commences. However, it is possible, and does occur, that the bedknife will move relative to the cutting reel during operation of the mowing machine. This might be caused by vibration or by the cutting unit passing over a rock or the like in the area being cut. Once the initial adjustment changes, the cutting unit will be not properly adjusted for the remainder of the mowing operation. There is no way using the manual method of adjustment to correct the position of the bedknife during the actual mowing operation itself.